Wing Tips STAY UP!


The following was taken from the 4th Lazair newsletter:

“In the last update, we advised against making design changes in the Lazair unless you are qualified to predict the consequences of the changes.  Since then, we have received a report of a situation which illustrates the point rather dramatically.

Most Lazair owners are probably used to having people ask why the wingtips are turned up rather than down (since the trend on many light airplanes is toward down turned wingtips).  Down turned tips tend to increase lift, but since the Lazair was designed around a very high lift airfoil, the additional lift provided by downturned tips is not necessary.  What ~ necessary, is a smooth airflow over the ailerons (to increase their effectiveness), and a force which will lift the leading wingtip if the aircraft tends to slip sideways.  

One Lazair owner decided to redesign his aircraft by installing the wingtips upside down.  Fortunately, he had the foresight to have the aircraft test flown by his local Ultraflight distributor who is a commercial pilot with a wealth of flying experience.  During the initial phase of the test flight, while executing gentle maneuvers, everything appeared normal.  However, after entering a turn with a very high angle of bank, the aircraft began to slip into the turn and refused to come out of it.  Only by using every bit of his skill and knowledge was the pilot able to regain control, and in doing so, he lost nearly 600 feet of altitude. This Is exactly the same characteristic which was related to us at Oshkosh this summer by the owner of a Mirage (which  incidentally has down turned wingtips). 

There is nothing in this world which is so perfect it cannot be improved – not even the Lazair – but the message should be clear.  If you do not know what you’re doing) don’t change it!”

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